Vinyl esters of dialkylhydroxyphenyl alkanoates

ABSTRACT

VINYL ESTERS OF DIALKYLHYDROXYPHENYL ALKANOATE MONOMERS ARE PREPARED BY A DIRECT REACTION OF ACETYLENE WITH AN APPROPRIATE ACID OR THE ACIDOLYSIS OF VINYL ACETATE OR ISOPROPENYL ACETATE. THESE MONOMERS CAN BE POLYMERIZED WITH A FREE RADICAL INITIATOR YIELDING POLYMERIC MATERIALS WHICH WILL PROTECT ORGANIC MATERIALS IN GENERAL AND PARTICULARLY, SYNTHETIC POLYMERS SUCH AS POLYOLEFINS AGAINST OXIDATIVE AND THERMAL DEGRADATION.

United States Patent 3,708,520 VINYL ESTERS OF DIALKYLHYDROXYPHENYLALKANOATES Martin Dexter, Briarclilf Manor, John D. Spivack, SpringValley, and David H. Steinberg, Bronx, N.Y., assignors to Ciba-GeigyCorporation, Greenburgh, N.Y. No Drawing. Filed June 1, 1971, Ser.-No.149,049- Int. Cl. C07c 69/76 US. Cl. 260-473 S 7' Claims ABSTRACT OF THEDISCLOSURE Vinyl esters of dialkylhydroxyphenyl alkanoate monomers areprepared by a direct reaction of acetylene with an appropriate acid orthe acidolysis of vinyl acetate or isopropenyl acetate. These monomerscan be polymerized with a free radical initiator yielding polymericmaterials which will protect organic materials in general andparticularly, synthetic polymers such as polyolefins against oxidativeand thermal degradation.

The monomeric compounds of this invention which are vinyl esters ofdialkylhydroxyphenyl alkanoates or oxyalkanoates can be represented bythe following formula:

(lower) alkyl (lower) alkyl wherein R is hydrogen or methyl group,

n is 0 to 6, straight or branched, preferably 0 or 2; and m is 1 to 6,preferably 1 or 2.

Lower alkyl groups containing up to and including 6 carbon atomsillustratively include methyl, ethyl, n-propyl, isopropyl, n-butyl,t-butyl, hexyl, and the like. These groups are substituents on thephenolic group. One alkyl substituent is in a position ortho to thehydroxy group and a second alkyl group is either (a) in the otherposition ortho to the hydroxy group or (b) in the position meta to thehydroxy group and para to the first alkyl group. Preferred are thedialkyl-4-hydroxyphenyl groups wherein the alkyl groups are branchedgroups such as isopropyl, t-butyl or t-amyl. However, other arrangementsare also contemplated, such as 3-t-butyl-6-methyl-4-hydroxyphenyl group,3,5-di-isopropyl 4 hydroxyphenyl group, 3,5-di-t-hexyl 4 hydroxyphenylgroup, 3,5-di- (lower)alkyl i? HECH HOG-A- (lower)alkyl (lower)alkyl itCH=CHO A- OH (lower-)alkyl 3,708,520 Patented Jan. 2, 1973 ice (b) theacidolysis of vinyl acetate or isopropenyl acetate (lower)alkyl O 4% (lCH2=CHO CH3 H0 A.

10 er alkyl w (lower)alky1 O CHFCHO ("J-A- OH (1ower)alkyl (lower)alkyl(I) O CH2=C(CH:)-O(LJ OH: H0 -A- 0H -v lower alk l y (lower)alkyl 1CH2=C (CH;)O( JA OH 7 (lower)alky1 as described in C. E. Schildknecht,Vinyl and Related Polymers, pages 323-385 (I. Wiley & Sons, Inc., NewYork 1952).

The preferred method, if the synthesis is carried out on a laboratoryscale, in method (b), described in detail in Example 1 in thepreparation of vinyl 3-(3,5-di-t-butyl-4- hydroxyphenyl)-propionate.

The procedures used in preparing the hindered phenolic acids employed inthe preparation of the monomers of this invention and listed in Table Ibelow have been disclosed in the prior art. The syntheses of these acidsinclude the reaction of alkali metal salts of an alkylated phenol withmethyl acrylate; the reaction of alkali metal salts of alkylated phenolswith esters of a-haloalkanoic acids; the reaction of alkylhydroxybenzylchlorides with alkali metal cyanides to obtain alkylhydroxyphenylacetmnitriles followed by hydrolysis to the acids.

Where esters are prepared by the above mentioned methods," the freeacids can be obtained by hydrolysis of the ester with sodium hydroxide.The preparation of some of the acids employed herein is also describedin US. Pat. 'No. 3,249,632. 1

The monomeric compounds of this invention can be homopol ymerized orcopoly-merized with other ethylenically unsaturated monomers employingfree radical initiators. The initiators useful in the polymerization ofthese monomers are azoalkyl nitriles or azoarylnitriles which dissociateinto alkyl or aryl radicals at temperatures convenient forcopolymerization reactions. The best known example of an azo nitrile is2,2'-azo-bis-isobutyronitrile and the dissociation providing therequired alkyl radicals. Also useful in said polymerizations are alkylperoxides or aryl peroxides which decompose into alkyl or aryl radicals.The polymers formed from the polymerization of the monomers of thisinvention contain hindered" phenolic groups and therefore are useful asantioxidants for organic materials subject to oxidative and/or thermaldegradation. These polymers are particularly useful as antioxidants forpolyolefins such as polypropylene or polyethylene. However, othersynthetic polymers can also be stabilized by the polymeric antioxidantsprepared from the monomers of this invention. The preparation of thepolymers from said monomers and their use as antioxidants for organicmaterials are described in greater detail in the copending applicationSer. No. 68,563, filed Aug. 31, 1970.

The following are presented to further illustrate the present inventionwithout introducing any limitation thereto 3 EXAMPLE 1 Vinyl3-(3,S-di-t-butyl-4-hydroxypheny1)propionate A solution consisting of13.9 g. (0.05 mole) of 3-(3,5- di-t-butyl-4-hydroxyphenyl) propionicacid and 43.0 g.

4 C./ 0.05 mm. There was obtained 1.00 g. (95% recovery) of sublimatehaving melting point 72-5 C. and whose NMR spectrum conformed to theexpect structure.

Analysis.Calcd for C H O (percent): C, 74.96; H, 9.27. Found (percent):C, 75.12; H, 9.17.

(0.50 mole) of redistllled vinyl acetate was treated with 0.2 Employmgthe method described in Example 1, the g. of mercuric acetate whilestirring at 50 C. After 15 minfollowing vinyl esters are prepared fromvinyl acetate or utes, 0.02 ml. of 100% sulfuric acid was added and theisopropenyl acetate and the listed acids containing hinreaction mixturerefluxed in nitrogen atmosphere for 3 dered phenolic groups:

TABLE I Examples Vinyl ester if i I CH2=CHOCCH3 1100- OH CHa=OHO OH 3 ui ii QH =CHOCCH HOd- OH CH2=CH0C H II H i! CH2=CHOCCH3 HOC OH CH=CHOCCH---0H 5---.'..'.".;.:: O H (H) CHl=CHO iCm HOCCHzO- OH CHzzCHOCCHaO- 0H III N CHFC(CH3)O(JJCH3 HOCCHZCH OH CHz=C(CH )OCCH2CH --OH t 0H =CH0iiCmHOi ICH -CH OH CH=C(OH3)OCCH:CH@OH CHz- -C(CH )0( iOH HOi IOHZOH -OHCH2=C(CH )OOCHzCHz@-OH 9 f fl 1 0Hz=GHo iCH3 HOCOH CHz-@OH CH:=CHO(JOHzCHg 0H CHz=CHOi JCHa H0 i l (GH2)0 In the above Table I, thesubstituents on the phenyl ring are defined as follows: (a straightline) denotes methyl group; denotes lsopropyl group; denotes tert-butylgroup.

hours. The reaction was cooled and neutralized with 0.5 g. of sodiumacetate (Na C H O 3H 0). The solution was decanted from the insolublesolids and stripped of volatiles, leaving 16.5 g. of residue. This wasdissolved in ml. of benzene and passed through a bed of 144 g. ofalumina (Woehn, neutral, activity II). The alumina was washed with anadditional 200 ml. of benzene. Removal of the solvent afforded 12.7 g.(83.5% yield) of product which spontaneously crystallized to a whitesolid having melting point 70-74 C. The product was crystallized from 50ml. of hexane with ice bath cooling to give by treating 1.05 g. in asublimation apparatus at EXAMPLE 11 Isopropenyl3-(3,5-di-t-butyl-4-hydroxyphenyl)- propionate The procedure of Example1 was followed except that vinyl acetate was replaced with isopropenylacetate yielding the above named product.

EXAMPLE 12 Vinyl 3,5-di-tert-butyl-4-hydroxybenzoate Following theprocedure of Example 1, vinyl acetate is reacted with3,5-di-t-butyl-4-hydroxybenzoic acid yielding the above named product.

5 EXAMPLE 13 Vinyl 3,5 -di-tert-butyl-4-hydroxyphenoxy acetate 1. Acompound having the formula (lower) alkyl 0 CH =C(R)OiL A- 0H ower)alkyl wherein R is hydrogen or methyl group, A is a group ---C,,H or C HO, n is 0 to 6, and m is 1 to o.

2. A compound according to claim 1 wherein A is a group -C H 3. Acompound according to claim 1 wherein (lower) alkyl groups aretert-butyl groups and both are located in positions ortho to the hydroxygroup.

4. A compound according to claim 1 wherein A is C, H n is zero or 2 and(lower)alkyl group is tertbutyl.

5. A compound according to claim 1 which is vinyl 3- (3,5-di-t-butyl-4-hydroxyphenyl propionate.

6. A compound according to claim 1 which is isopropenyl3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate.

7. A compound according to claim 1 which is isopropenyl3-(3,S-dimethyl-4-hydroxyphenyl) benzoate.

References Cited FOREIGN PATENTS 9/1964 Canada 260473 S U.S. Cl. X.R.260-473 G

